第15周作业

题目1：编写一个应用程序，输入用户名和密码，访问test数据库中t_login表（字段包括id、username、password），验证登录是否成功。

题目2：在上一题基础上，当登录成功后，将t_user表（id、name、sex、birthday）的信息进行显示（要求使用DB.java完成登录和获取t_user表中数据的操作），最后再对t_user表进行一条记录的添加操作。

代码

Test类

package ccut.hou;
import java.sql.*;
import java.util.Scanner;

public class Test{
    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        System.out.println("请您输入用户名和密码:");
        String  username = reader.next();
        String password = reader.next();
        Connection con = null;
        Statement st = null;
        ResultSet rs=null;
        //处理异常
        try {
            Class.forName("com.mysql.jdbc.Driver"); //加载驱动
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db","root","");
            st = con.createStatement();
            String sql ="insert into t_login(username,password) values('" +username+ "','" + password + "')";

            int count =st.executeUpdate(sql); 
            if(count>0) {
                System.out.println("登陆成功");
                rs= DataBase.getInstance().executeSelect("select * from t_user", args);   //查询表

                while(rs.next()) {  
                    int id = rs.getInt(1);
                    String name = rs.getString(2);
                    int sex = rs.getInt(3);
                    String birthday = rs.getString(4);
                    System.out.println("id\t"+"name\t"+"sex\t"+"birthday");
                    System.out.println(id + "\t" + name + "\t" + sex + "\t" + birthday);
                }
                
                
                System.out.println("请输入id，name，sex，birthday：");//增加一条记录
                String id=r.next();
                String name=r.next();
                Integer sex = Integer.valueOf(r.next());
                String birthday = r.next();
                String sql1="insert into t_user(id,name,sex,birthday) values('"+id+"','"+name+"','"+sex+"','"+birthday+"')";
                int Count=DataBase.getInstance().executeModify(sql1, args);
                if(Count>0)
                    System.out.println("添加成功");
                else
                    System.out.println("添加失败,填写有误");
            }
            else
                System.out.println("登陆失败");


        } catch (ClassNotFoundException | SQLException e) { //处理异常
            e.printStackTrace();
        }finally {
            try {
                st.close();
                con.close();
            }catch (SQLException e){
                e.printStackTrace();
            }
        }
    }
}

DataBase类

package ccut.hou;
import java.sql.*;//导入Sql包
public class DataBase { //创建类
    private Connection con;
    private PreparedStatement pre;
    private ResultSet rs;
    private static DataBase db;

    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");  //加载JDBC驱动程序
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    private DataBase(){   //构造方法
        try {
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db","root",""); //创建con
        } catch (SQLException e) {  //捕获异常
            e.printStackTrace();
        }
    }

    public static DataBase getInstance(){
        if(db == null){
            db = new DataBase();
        }
        return  db;
    }
    public ResultSet executeSelect(String sql,Object[] args){   //查
        try {
            pre = con.prepareStatement(sql);
            if (args.length!=0){
                for (int i = 0; i < args.length; i++) {
                    pre.setObject(i+1,args[i]);
                }
            }
            rs = pre.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
    public int executeModify (String sql, Object[] args) {//改
        int n = 0;
        try {
            pre = con.prepareStatement(sql);
            if(args.length !=0) {
                for(int i = 0;i< args.length;i++) {
                    pre.setObject(i+1, args[i]);
                }
            }
            n = pre.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return n;
    }
    public void close() {  //关闭数据库连接
        try {
            if (rs != null) {
                rs.close();
            }
            pre.close();
            con.close(); 
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

截图